The S5973-01 from Hamamatsu Photonics is a Photodiode with Wavelength Range 320 to 1000 nm, Capacitance 1.6 pF, Dark Current 0.001 to 0.1 nA, Responsivity/Photosensitivity 0.44 to 0.52 A/W, Active Area Diameter 0.4 mm. More details for S5973-01 can be seen below.